The Microsoft Exchange protocol documentation provides detailed technical specifications for the Microsoft protocols and extensions to industry-standard and other published protocols that are implemented and used by Microsoft Exchange.
The documentation is designed to describe each protocol in detail as it is used by Microsoft Exchange. Each specification documents technical requirements, limitations, dependencies, and specific protocol behavior.
The documentation includes companion overview and reference documents that supplement the technical specifications with conceptual background information, overviews of inter-protocol relationships and interactions, and technical reference information.
Download: Exchange Server Protocols PDF .zip file (latest)
Download: Microsoft Exchange Server Protocol Documentation (March 2015 version)